1. Field of the Invention
The present invention relates to a field of battery technology, in particular to a battery array voltage equalization device.
2. Background of the Related Art
Batteries are normally serially-connected or connected in parallel in order to gain higher output voltage and larger power capacity to meet the requirements of load-driving. Because of the better performance-to-cost ratio, the rechargeable batteries have been widely used in various electric products, and also in automobiles. However, as limited by the processing condition, differences exist between every single cell. After multiple cycles of charging and discharging, voltage levels differ among the batteries. Thus, the effective capacity of the serially connected battery array decreases, which influences the performance and the lifespan of the battery array.
To solve this problem, researches have been done on the battery equalization methods. At present, one battery equalization circuit comprises a detecting circuit, a control unit and an energy dissipation circuit. The detecting circuit detects the voltage of the two electrodes of each battery and transmits the detected voltage signals to the control unit. The control unit compares the detected voltage signals and finds out the lowest voltage in the detected voltages signals. Based on the lowest voltage signal, the control unit controls the energy dissipation circuit to discharge the batteries whose voltage levels are higher than the lowest voltage value, therefore equalizing the battery voltages in a battery array. In such an equalization scheme, the energy dissipation unit works constantly, therefore the batteries stay in a status of charging or discharging, which influences the capacity of each battery. Meanwhile, the energy dissipation circuit generates ripple wave which causes fluctuation in the battery voltage.